The present invention relates generally to a combined wireless voltage controlled dimming interface for a light emitting diode (LED) driver. More particularly, the present invention relates to enabling a plurality of control devices to be communicatively coupled to a control module associated with an LED driver using a shared interface, the shared interface being configured to provide operating power to one or more control devices during operation.
LED lighting is growing in popularity due to decreasing costs and long life compared to incandescent lighting and fluorescent lighting. LED lighting can also be dimmed without impairing the useful life of the LED light source.
An exemplary configuration of an LED lighting system 10 including a dimmable LED driver 14 is represented in FIG. 1. As shown, a dimmable LED driver 14 is positioned between an AC power source V_AC_in 12 (e.g., an AC mains input) and an LED lighting module 16. The LED driver 14 is configured to regulate a DC current passing through the LED lighting module 16 and to receive control signals from a control module 18. The LED lighting module 16 is configured with a plurality of LEDs LED1, LED2, . . . LEDn that receive power from the LED driver 14.
FIG. 1 illustrates a communication control module 18 having separate interfaces for 0-10 volt dimming and wireless control modules in the related art. The dimmable LED driver 14 may be configured to operate according to a dimming control signal driver_ctl based on input received from a 0-10 volt dimmer 24 and wireless control module 26 as shown in FIG. 1. In the illustrated configuration, there are four control input lines: two control lines (corresponding to signals Ctl+ (e.g., via a purple+ wire) and Ctl− (e.g., via a grey− wire)) for 0-10 volt dimming control and two control lines (e.g., corresponding to signals W_Ctl+ and W_Ctl−) for the wireless control module 26. The wireless control module 26 may be configured to receive an external input signal, for example, using wireless communication protocols such as ZIGBEE® or BLUETOOTH®.
A DC voltage is provided from the control module 18 to a lighting dimmer, such as 0-10 volt dimmer 24, via Ctl+ and Ctl− signal lines. One or more of the Ctl+ and Ctl− signals may be received by a dimming and tuning circuit 22 of the control module 18 and processed at a microcontroller 20 of the control module 18. The microcontroller 20 is configured to transmit a control signal driver_ctl to the LED driver 14 during operation based upon signals received from the dimmer 24 or a wireless control module 26. The wireless control module 26 is configured to communicate one or more LED driver control signals to the control module 18 via W_Ctl+ and W_Ctl−. The control module 18 receives control signals from the dimmer 24 and the wireless control module 26 and determines and transmits a control signal driver_ctl for output to the LED driver 14.
While the dimmer 24 and wireless control module 26 may be separately interfaced with the control module 18, difficulties arise when device power requirements are not universal between disparate control devices and/or when a plurality of dimming and control signal sources are connected to the control module 18 via shared control lines. For example, systems having a plurality of dimming and control signal sources each having their own dedicated lines connected to the communication control circuit 18 results in a burdensome wiring configuration, multiple points of failure, and requires distinct power circuits and configurations.
One significant disadvantage of an implementation having an arrangement similar to that illustrated in FIG. 1 is that if the 0-10 volt dimmer 24 and wireless control module 26 share a common interface to the control module 18, the system is unable to provide the current required to operate the wireless control module 26. A dimming signal interface associated with the control module 18 may provide only a 250 μA constant current to the 0-10 volt dimmer 24 when the dimmer is connected to the interface. However, a wireless control module 26 may require more than 1 mA operating current when transmitting. This means that simply connecting the wireless control module 26 to an existing 0-10 volt dimmer 24 interface will not work.